Inaugurated by IN-SPACe
ISRO Registered Space Tutor
S3-SA4-0040
What is the Test for Divisibility by 5?
Grade Level:
Class 6
AI/ML, Data Science, Physics, Economics, Cryptography, Computer Science, Engineering
Definition
What is it?
The Test for Divisibility by 5 is a quick rule to check if a number can be divided by 5 completely, without leaving any remainder. A number is divisible by 5 if its last digit (the digit in the ones place) is either 0 or 5.
Simple Example
Quick Example
Imagine you have a stack of 75 rupees notes. Can you divide them equally among 5 friends without anyone getting less or more? Yes! Because 75 ends with a '5', it means 75 is divisible by 5. Each friend would get 15 rupees.
Worked Example
Step-by-Step
Let's check if the number 230 is divisible by 5.
Step 1: Look at the last digit of the number 230.
---
Step 2: The last digit of 230 is 0.
---
Step 3: According to the divisibility rule for 5, if the last digit is 0 or 5, the number is divisible by 5.
---
Step 4: Since the last digit is 0, 230 is divisible by 5.
Answer: Yes, 230 is divisible by 5.
Why It Matters
Knowing divisibility rules helps you solve problems faster in competitive exams and everyday calculations. In Computer Science, these rules are part of basic number theory used in algorithms. Even in Economics, quickly grouping data often uses similar logic, making calculations more efficient.
Common Mistakes
MISTAKE: Checking if the first digit is 0 or 5. | CORRECTION: Always check the LAST digit (the digit in the ones place) of the number.
MISTAKE: Confusing divisibility by 5 with divisibility by 2 (which checks for even numbers). | CORRECTION: Divisibility by 5 specifically looks for 0 or 5 at the end, while divisibility by 2 looks for 0, 2, 4, 6, or 8.
MISTAKE: Thinking that any number with a 5 in it (like 52) is divisible by 5. | CORRECTION: Only the digit at the very end matters. 52 is not divisible by 5 because its last digit is 2, not 0 or 5.
Practice Questions
Try It Yourself
QUESTION: Is the number 145 divisible by 5? | ANSWER: Yes
QUESTION: Which of these numbers is NOT divisible by 5: 30, 55, 72, 100? | ANSWER: 72
QUESTION: A shopkeeper has 248 laddoos. Can he pack them into boxes of 5 laddoos each without any laddoos left over? | ANSWER: No, because 248 ends in 8, not 0 or 5.
MCQ
Quick Quiz
Which of the following numbers is divisible by 5?
123
451
670
892
The Correct Answer Is:
C
A number is divisible by 5 if its last digit is 0 or 5. Out of the given options, only 670 has 0 as its last digit, making it divisible by 5.
Real World Connection
In the Real World
Imagine you are a cashier at a grocery store in India. If a customer buys items totaling 345 rupees, you know instantly that you can give them change in 5-rupee coins or notes without a problem, because 345 ends in 5. This quick check helps you manage cash efficiently and quickly.
Key Vocabulary
Key Terms
DIVISIBILITY: The ability of one number to be divided by another number without a remainder. | REMAINDER: The amount left over after a division when one number does not divide another exactly. | LAST DIGIT: The digit in the ones place of a number. | ONES PLACE: The rightmost digit in a whole number.
What's Next
What to Learn Next
Great job understanding divisibility by 5! Next, you should explore the 'Test for Divisibility by 10'. It's very similar and builds directly on what you've learned here, making it easy to grasp.
